U.S. Army nurses Capt. Gladys E. Sepulveda, left, of Ponce, Puerto Rico, and 2nd Lt. Lois Ferrari, of Pittsburgh, Pa., rest on sandbags at Cam Ranh Bay in South Vietnam, during the Vietnam War on July 14, 1965. They two were waiting transportation to Nha Trang, to work in the 8th field hospital.

Credit: AP Photo

Marine Corps Women Reserves undergoing training at Camp Lejeune, New River, N.C., ride in a landing boat of the type that were used by the Marines in landing operations in the South Pacific, Oct. 2, 1943.

Credit: AP Photo

A group of Women Army Corps (WAC) personnel pose in a Tokyo lounge on March 1947.

Credit: AP Photo

Women Army Corps (WAC) switchboard operators put military calls through at their base in France, Oct. 7, 1944.

Credit: AP Photo

Five members of the Women's Army Corps serving with the army service of supplies, salute an officer at a base in England, May 5, 1944.

Credit: AP Photo

Nancy Morgan Hart, an American colonist living in Georgia defends her home and children against invading British soldiers during the American Revolutionary War in this undated illustration. According to legend, Hart captured and killed British soldiers during the war.

Credit: AP Photo

Mrs. Eloise J. Ellis has been appointed by civil service to be senior supervisor in the Assembly and Repairs Department at the Naval Air Base, Corpus Christi, Texas, in August 1942.

Credit: Library of Congress

An Iraqi woman is searched by a female U.S. soldier before reuniting with her husband, who was among 32 men released from U.S. military detention at Camp Bucca in Tarmiyah, 30 miles north of Baghdad, Iraq, April 12, 2009.

Credit: AP Photo/Maya Alleruzzo

U.S. Army Spec.Tanya Miller of New York., leans against a wall on an airbase in Saudi Arabia, Sept. 3, 1990. Miller was in Saudi Arabia with the 101st Airborne Divsion in support of Operation Desert Shield.

Credit: AP Photo/David Longstreath

Army Spc. Monica Brown, a medic from the 782nd Brigade Support Battalion, 4th Brigade Combat Team, 82nd Airborne Division, on March 20, 2008. She received a silver star at an award ceremony at Bagram Airfield, Afghanistan. Brown is the second female since World War II to earn the Silver Star award for her actions while in combat.

Credit: AP Photo/US Army, Spc. Micah E. Clare

Capt. Sara Rodriguez of the 101st Airborne Division walks through the woods during the expert field medical badge testing at Fort Campbell, Ky., May 9, 2012.

Credit: AP Photo/Kristin M. Hall

United States Marine Corps female recruit adjusts her Kevlar helmet Jan. 15, 2003, before re-entering the Combat Pool for another swim lesson during boot camp on Parris Island, SC.

Credit: Stephen Morton

Ruti, a female combat medic serving in the Armored Corps, unwinds Feb. 28, 2002, at the Salem checkpoint on the Israel-West Bank border after returning from an incursion into the West Bank town of Jenin to evacuate a wounded soldier.

Credit: David Silverman/Getty Images

United States Marine Corps female recruits Lynn Vida of New Jersey sips hot chicken broth Jan. 15, 2003, during a short break from the Leadership Reaction Course that is part of The Crucible on Parris Island, SC.

Credit: Stephen Morton/Getty Images

Female Marine Corps recruits wait for a turn to shoot on the rifle range at the United States Marine Corps recruit depot June 21, 2004, in Parris Island, S.C.